Water utility companies provide water to customers through a network of water pipes. The size of pipes may vary depending on the volume of water that is designed to flow through a particular section of pipe. For example, large water mains may provide water transportation to a location farther away from the source of the water and the size of pipes may decrease as the volume and distance from the source decreases. One concern for water utility companies, as well as the owners and operators of other fluid distribution and transportation systems, is the loss of fluid through leaks in the pipes. Not only do fluid leaks waste fluids, such as clean potable water, but sometimes unwanted contaminants may be introduced into the fluid system from outside the system through the point of the leak.
Piezoelectric vibration sensors are a type of vibration sensor that typically include a piezoelectric crystal capable of generating a current when the crystal is bent during vibrations. The piezoelectric crystal is typically attached to a base of the vibration sensor and another piezoelectric crystal may be attached to the base such that the base is between the two piezoelectric crystals. The vibration sensor may also include more than two piezoelectric crystals or more than one base. The current from the one or more piezoelectric crystals during vibration can then be detected to sense vibrations. Fluid systems such as water distribution systems may vibrate when a leak is present in the system, and a vibration sensor can detect these vibrations to signal when the system should be shut down, inspected, or treated to repair the leak. Leaks in fluid systems in various conditions and situations may produce different vibrations in different frequency ranges, requiring vibration sensors attached to the systems to be calibrated to respond appropriately during a desired frequency range that would indicate a leak for a particular system in a particular situation. In some situations, leaks in a fluid system fall within a frequency range typically lower than the frequency detection range of typical piezoelectric vibration sensors. Therefore the vibration sensor requires a specific resonance frequency that is specifically tailored to fall within the frequency range of typical leaks of the specific fluid system to which the vibration sensor is attached to. The reverse also holds true in some situations where it is desired that the resonance is outside the measured frequency range if there is a possibility of amplifying ambient noise or distorting the frequency profile.